1. Field of the Invention
The present invention relates to a condenser tube for use in a heat exchanger.
2. Description of the Prior Art
Heat exchangers normally include a pair of tanks or headers and a plurality of condenser tubes. The headers include header walls which are spaced from and face one another. The condenser tubes extend between the headers and convey cooling fluid through the header walls and into the closed headers. A plurality of fins extend between adjacent condenser tubes for transferring heat from the tubes to air passing through the heat exchanger to ultimately cool the fluid in the tubes. Such condenser tubes are frequently separated into a plurality of channels.
A method of forming a flat strip into such a condenser tube having two ends separated by a pre-determined tube length and two channels extending between the ends is disclosed in the U.S. Pat. No. 6,615,488 to Anders et al. The flat strip is progressively formed via a series of roller stations until the edges are folded into a pair of central abutting flanges engaging the inner surface of the strip along the center. The result is a continuous enclosed B-shaped tube with two channels extending the length of the tube and with the central abutting flanges forming channel sides which separate the channels from one another. The B-shaped tube is then severed to separate it into successive condenser tubes each of the pre-determined tube length.
It is also well known to produce such a condenser tube but having additional channels extending between the ends. The method includes moving the strip through a plurality of forming operations to form a continuous enclosed tube separated into channels by the longitudinally parallel channel sides and severing the enclosed tube to separate the enclosed tube into successive condenser tubes of the pre-determined tube length. Typical severing operations include sawing and die cutting.
In sawing, cutting residue contaminants, such as metal shavings or particles or cutting lubricants, penetrate the openings and either plug or otherwise contaminate the severed sides of the channels. Because of the small size of the individual channels, it is difficult to remove these contaminants.
In a die cutting operation, the blade of the die is moved across and through the entire enclosed tube to sever the exterior of the tube as well as the channel sides. Even with a new die and a sharp blade, some distortion of the channel sides occurs. As the blade dulls, the degree of the distortion increases and the severed edges of the individual condenser tubes become severely distorted.
Whichever severing technique is utilized, undesirable distortion and/or contamination occurs.